The present invention relates to the automatic packaging of products, in particular rolls of toilet or kitchen paper, wrapped in collective packs using a film of packaging material.
The invention relates in particular to a method for stopping and restarting an automatic machine for packaging these products, advantageously used to optimize production changeover time and to minimize the number of manual operations to be performed for this purpose by personnel attending to the machine.
According to current packaging industry practices in the field of the above mentioned products, changing over to a different type of product, for example, when a programmed quantity of products has been reached, means stopping an automatic packaging machine and subjecting it to a whole range of operations in order to adapt its parts and settings to the different product. The completion of the setup and changeover procedure, however, involves numerous operations which must be performed manually and in a set order that must rigidly observed.
Basically, these operations are the following: stopping the machine; removing the products remaining from the previous production runs; setting the machine up for the new size packages to be made; filling the machine with products for the new size packages; and restarting the machine gradually before returning it to normal production speed.
More specifically, these operations include:
manually stopping the means that feed the product to the machine;
manually activating the function that removes the rolls of the previous production run from the feed means and from the inside of the machine itself;
manually removing from the machine the sheets of wrapping film remaining from the previous production run;
manually substituting the film reel from which the product wrapping sheets for the previous production run were drawn;
manually loading the end of the film on the substitute reel into the related film feed means;
performing a few machine cycles at reduced speed in manual, jogging mode in order to stabilize the wrapping film last loaded;
re-starting the product feed system using the control panel and screen;
performing a few machine cycles in manual mode in order to fill the roll feed system;
manually removing the wrapping film sheets made during the test cycles;
performing a few machine test cycles in manual mode; and lastly,
manually switching to automatic mode and waiting for the machine to reach steady-state operating conditions.
The operations listed above, must be performed (some manually and others semiautomatically, for example, by jogging the machine) in a well-defined order constituting a rigid procedure that must be followed for machine setup to be as quick and effective as possible.
Procedures of this kind as guides for machine users are extremely useful tools which greatly simplify changeover operations compared to the situation existing prior to their advent.
However, manual operations or operations that must be performed under human supervision introduce a certain degree of unpredictability that may nullify these benefits. Thus, positive results may not be attained simply on account of the operator""s failing to follow a procedure exactly, either deliberately or due to negligence, or, for any reason, incorrectly performing, or dedicating too much time to, one or more of the steps in the procedure, meaning that the time taken to set up and restart the machine may become unduly long, with obvious negative repercussions on production costs and scheduling.
In order to improve on this state of affairs, the invention has for an aim to provide a method that automates the changeover procedure to a much greater extent than prior art solutions and significantly reduces the number of operations that have to be performed manually.
According to the invention, this aim is achieved through a method for stopping and restarting an automatic machine for wrapping products, in particular rolls of toilet or kitchen paper, in a collective pack using a packaging film unwound from a first reel, the method comprising the following automatic sequence of steps, triggered by the activation of a machine stop control:
reducing machine speed to a speed suitably lower than the working speed;
stopping the infeed of the products to the machine;
stopping the infeed of the wrapping film to the machine with a delay of at least four steps after stopping product infeed;
stopping the machine after the products inside the machine have moved at least three steps forward;
the method further comprising the steps of
substituting the first reel of wrapping film with a second reel;
loading the film on the second reel into the related film feed means;
restarting the machine and thereby automatically activating the following sequence of steps:
restarting wrapping film unwinding from the second reel;
positionally centering the wrapping film;
restarting the machine at a reduced speed, lower than the working speed;
restarting product infeed;
restarting the infeed of the sheets of wrapping film to the machine with a delay of at least four steps after restarting product infeed.